The present invention refers to an apparatus for continuously measuring the hydrocarbon concentration in a gas flow.
Hydrocarbon concentrations in a gas flow can be measured by using a flame ionization detector with a combustion chamber in which burner gas such as hydrogen, an oxidizer such as synthetic air and sample gas to be tested is introduced. The flame ionization detector includes a burner with electrodes in vicinity of the burner flame. A direct voltage is applied to the electrodes, and the ionization in the area of the burner flame results in a current flow between the electrodes which is a function of the portion of hydrocarbons in the sample gas to be tested and is about directly proportional to the number of hydrocarbon atoms introduced into the flame per unit of time.
The principle of flame ionization and the use of flame ionization detectors are known and their application is wide spread, such as e.g. for exhaust gas measurement in motor vehicles, in the chemical and petrochemical industry, electrical industry, in the area of coating plants e.g. for the furniture industry during coating of chip boards with veneer, or in the packaging industry when webs of carrier material should be laminated at one side or at both sides with a coating of plastic material.
All known methods and apparatuses are characterized by pumping the sample gas, the burner gas and the oxidizer into the combustion chamber of the flame ionization detector at overpressure. This is disadvantageous for a variety of reasons such as safety reasons or inaccuracy of the measurement.